This invention relates to a system for detecting the presence of an object within a space, and more particularly to an object detection system for use in connection with a mobile storage system.
Mobile storage systems typically include a series of mobile storage units mounted to rails or the like and movable toward and away from each other in response to operation of a drive arrangement associated with each mobile storage unit. A mobile storage system typically includes stationary end units with a series of movable storage units located between the end units. Movement of the mobile storage units functions to create an access aisle between two of the units. As the aisle opens, the other storage units are positioned in close side-by-side relationship to minimize the overall floor space required for the storage units.
In the past, it has been known to provide a sweep or safety switch bar for notifying the control system associated with the drive arrangement of each storage unit to stop motion of the storage unit if an obstacle or impediment to movement is encountered. This type of arrangement is illustrated in U.S. Pat. Nos. 4,743,078 and 4,733,923, the disclosures of which are hereby incorporated by reference. This type of system prevents the storage units from closing, but typically involves the storage units moving close together before an obstacle is encountered. A photoelectric sweep is disclosed in U.S. Pat. No. 5,121,975, the disclosure of which is hereby incorporated by reference. This type of system provides an alternative arrangement, but still results in movement of the storage unit quite close to a person before movement of the storage unit is interrupted.
U.S. Pat. No. 5,427,444, also incorporated by reference, shows a directional detector for use with a mobile storage system, which detects entry of an obstacle into the aisle and prevents movement until the obstacle is detected to have left the aisle. While this type of system is satisfactory, it involves use of a number of stationarily mounted light source-light detector pairs mounted at various locations along the length of each of a pair of adjacent storage units. U.S. Pat. No. 5,417,487 shows use of a motion detector for indicating the presence of a person between storage units, for preventing movement of the storage units when a person is present in the aisle.
It is an object of the present invention to provide an improved system for detecting the presence of an object in an aisle or space, particularly in connection with a mobile storage system. Another object of the invention is to provide such a system which provides high resolution, i.e. the ability to detect relatively small objects located within the aisle. A still further object of the invention is to provide such a system which can be used in connection with mobile storage units of varying length, and which provides the same degree of accuracy, reliability and resolution for any length of storage unit. A still further object of the invention is to provide such a system which is relatively simple in its components and installation, and requires little modification to the storage units.
In accordance with the invention, an object detection system for use in detecting the presence of an object within a space, such as within an aisle located adjacent a mobile storage unit in a mobile storage system, includes a light source which emits a light beam, and which is movable so as to move the light beam across the space. The light source is positioned toward a first side of the space and emits the light beam in a direction toward the second side of the space. The space further defines a first end and a second end, and the light source is positioned toward one of the ends of the space. A second light source is positioned toward the other end of the space, and is positioned so as to move a light beam across the space in a direction opposite that of the first light source. The first and second light sources are preferably pivotable so as to move the light beams across the space in a fan-type or sweeping motion.
The invention further includes a receiver or detector located toward each side of the space. In a preferred form, a series of reflectors are also positioned toward each side of the space. The reflectors function to reflect each light beam toward the side of the space from which the light beam is emitted, and each receiver receives the reflected light beams as light pulses. The presence of an object within the space functions to obstruct passage of the light beam from one of the emitters toward at least one of the reflectors, such that a light beam is not reflected back toward the receiver on the side of the space from which the light beam is emitted. This obstruction in the passage of the light beam provides a signal indicative of the presence of an object within the space, and a control system interconnected with the light beam receiver functions to prevent movement of the mobile storage unit in response to the signal when an object is present within the space.
In one form, each receiver is mounted adjacent one of the emitters in an emitter/receiver combination unit, to detect the reflected light pulses in generally the same location from which the light beam is emitted. Each emitter/receiver unit is preferably located within a housing, and is pivotably movable in response to operation of a motor located within the housing.
The emitter/receiver units may be mounted to adjacent storage units located one on either side of the space, with a series of reflectors being mounted to the mobile storage unit opposite each emitter/receiver unit. Alternatively, the emitter/receiver units and reflectors may be mounted in other locations, such as to stationary cabinets or walls, and may be mounted such that the light beams pass below the mobile storage units.
Each emitter/receiver unit may also include a secondary receiver arrangement, which directly receives the light beam emitted by the opposite emitter/receiver unit. Each secondary receiver arrangement is interconnected in the control system for the opposite emitter/receiver unit, and controls operation of the emitter portion of the opposite emitter/receiver unit to operate the emitter only when it is directed across the space.
The invention further contemplates an improvement in a mobile storage system as well as a method of detecting the presence of an object within a space, substantially in accordance with the foregoing summary.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.